1. Field of the Invention
The present invention relates to methods and apparatus of fabricating a semiconductor device. More particularly, the present invention relates to methods and apparatus of etching an edge portion of a wafer for fabricating the semiconductor device.
2. Description of the Related Art
As information and telecommunication technology improve, semiconductor technology has been developed to improve the integration degree, reliance and response speed of semiconductor devices. Single crystals of silicon may be formed on a silicon substrate, such as a silicon wafer, and various layers may be formed on the substrate. The various layers can be formed into patterns having desired electrical characteristics.
Fabrication processes for the semiconductor devices can include one or more of the following: a deposition process, a photolithography process, an etching process, an ion implantation process, a polishing process and the like. Some processes may be performed sequentially to form the device. After one of the processes is completed on a wafer, various byproduct materials, for example, a metallic polymer and/or polysilicon, can be deposited and can remain on the edge portion of the wafer.
The byproducts on the edge portion of the wafer can function as a particle source, and therefore the yield at the edge portion of the wafer (or over the entire surface) of the wafer may be reduced. Accordingly, it may be advantageous to remove some or all of the byproducts.
Conventionally, the edge portion of the wafer was partially exposed, and a wet etching process was performed on the exposed edge portion of the wafer to remove or reduce the byproducts on the wafer. However, wet etching may result in difficulties in process controls and high processing costs because of the etchant(s) used and the relatively long operational time that may be needed to reduce or remove the byproducts.
The byproducts on the edge portion of semiconductor wafers may also be removed through a dry etching process. For example, U.S. Pat. No. 5,945,351 (issued to Josef Mathuni, et al.) proposes an apparatus and method of dry etching an edge portion of the wafer.
FIG. 1 is a cross-sectional view illustrating a conventional etching apparatus for removing an edge portion of a wafer.
Referring to FIG. 1, a conventional etching apparatus includes a chamber 10 into which an etching gas and an inert gas are supplied, a chuck 20 positioned in the chamber 10 to support a wafer W, a lower electrode 40 positioned along an edge portion of the chuck 20 and to which a high frequency voltage is applied, a gas dispersion plate 30 positioned over the wafer W for dispersing the inert gas to uniformly supply the inert gas onto a central portion of a top surface of the wafer, and an upper electrode 50 positioned over the wafer W opposite the lower electrode 40.
The gas dispersion plate 30 includes an insulation material and is positioned adjacent to the top surface of the wafer W. In this configuration, an edge portion of the wafer W is defined by the gas dispersion plate 30. That is, a lateral portion of the wafer W that is not covered with the gas dispersion plate 30 is etched away during the edge etching process.
The apparatus of FIG. 1 can be used to dry etch the edge portion of the wafer, and, in comparison with a wet etching process, the dry etching process can be relatively simple and the operation time for reducing or removing the byproducts on the edge portion of the wafer W can be relatively short.
However, it may be difficult to adjust the etching area of the edge portion of the wafer using the dry etching process described above. The etching area is defined by the gas dispersion plate 30. However, the gas dispersion plate 30 may be difficult, costly and/or time consuming to change. It may be desirable to vary the etching area of the edge portion of the wafer W based on differences in processing techniques and environments. Therefore, the etching area defined by the gas dispersion plate 30 may reduce the usable area of the wafer.